Dear,
Sy will be more than 1.5 * St, St = B 31.1 allowable stress at test temp, say 40 C., having same allowable stress
Thus, make a copy of the input file, consider the hydrostatic test as sustained with water content & keep operating temperature for analysis at 40 C & make an additional loadcase as 0.67 * sust loadcase; if this second loadcase fails in stress, you need temporary supports for hydrotest. Remember to change all spring hangers to +Y supports with no friction.
regards,
sam
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